CHANGES IN THE ELECTRO-ENCEPHALOGRAM FROM LIGATION OF THE CAROTID ARTERIES

Abstract

The electro-encephalogram is becoming recognized as a sensitive indicator of the status of the cerebral cortex. The most prominent feature characterizing the normal electro-encephalogram is the alpha rhythm, which has a frequency averaging about ten cycles per second. When the function of the cerebral cortex is suppressed, regardless of the cause, the associated electrical potentials become less rhythmic and are irregular in shape and amplitude, and the frequency decreases and becomes irregular, ranging from one to seven cycles per second. This random slow frequency was termed by Walter¹the "delta" wave. It may be confined to a local region in the vicinity of a tumor or it may be generalized as a result of some diffuse brain involvement. The present discussion concerns the study of the electro-encephalographic records in the case of ligation of the large vessels of the neck as a therapeutic measure for an intracranial saccular aneurysm.